Which of these method of class String is used to extract a substring from a String object?

Question

Java String substring() method returns the substring of this string. This method always returns a new string and the original string remains unchanged because String is immutable in Java.

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Java String substring() Methods
String substring() Method Important Points
Java String substring() Example
Checking Palindrome using substring() Method
Which methods of class String is used to extract a substring from a String object?
Which of these method of class String is used to extract?
Which one of the following method is used to make substring?
Which of these method of class String is used to obtain a length of String object?

Java String substring() Methods

Java String substring method is overloaded and has two variants.

substring(int beginIndex): This method returns a new string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string.
substring(int beginIndex, int endIndex): The substring begins at the specified beginIndex and extends to the character at index endIndex - 1. Thus the length of the substring is (endIndex - beginIndex).

String substring() Method Important Points

Both the string substring methods can throw IndexOutOfBoundsException if any of the below conditions met.
- if the beginIndex is negative
- endIndex is larger than the length of this String object
- beginIndex is larger than endIndex
beginIndex is inclusive and endIndex is exclusive in both substring methods.

Java String substring() Example

Here is a simple program for the substring in java.

package com.journaldev.util;

public class StringSubstringExample {

	public static void main(String[] args) {
		String str = "www.journaldev.com";
		System.out.println("Last 4 char String: " + str.substring(str.length() - 4));
		System.out.println("First 4 char String: " + str.substring(0, 4));
		System.out.println("website name: " + str.substring(4, 14));
	}
}

Output of the above substring example program is:

Last 4 char String: .com
First 4 char String: www.
website name: journaldev

Checking Palindrome using substring() Method

We can use the substring() method to check if a String is a palindrome or not.

package com.journaldev.util;

public class StringPalindromeTest {
	public static void main(String[] args) {
		System.out.println(checkPalindrome("abcba"));
		System.out.println(checkPalindrome("XYyx"));
		System.out.println(checkPalindrome("871232178"));
		System.out.println(checkPalindrome("CCCCC"));
	}

	private static boolean checkPalindrome(String str) {
		if (str == null)
			return false;
		if (str.length() <= 1) {
			return true;
		}
		String first = str.substring(0, 1);
		String last = str.substring(str.length() - 1);
		if (!first.equals(last))
			return false;
		else
			return checkPalindrome(str.substring(1, str.length() - 1));
	}
}

Here we are checking if the first letter and the last letter is the same or not. If they are not the same, return false. Otherwise, call the method again recursively passing the substring with the first and last letter removed.

You can checkout more string examples from our GitHub Repository.

Reference: Oracle API Doc

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method and Descriptionchar charAt(int index)

Returns the char value at the specified index.

int codePointAt(int index)

Returns the character (Unicode code point) at the specified index.

int codePointBefore(int index)

Returns the character (Unicode code point) before the specified index.

int

codePointCount(int beginIndex,
int endIndex)

Returns the number of Unicode code points in the specified text range of this String.

int compareTo(String anotherString)

Compares two strings lexicographically.

int compareToIgnoreCase(String str)

Compares two strings lexicographically, ignoring case differences.

String concat(String str)

Concatenates the specified string to the end of this string.

boolean contains(CharSequence s)

Returns true if and only if this string contains the specified sequence of char values.

boolean contentEquals(CharSequence cs)

Compares this string to the specified CharSequence.

boolean contentEquals(StringBuffer sb)

Compares this string to the specified StringBuffer.

static String copyValueOf(char[] data) static String

copyValueOf(char[] data,
int offset,
int count)

boolean endsWith(String suffix)

Tests if this string ends with the specified suffix.

boolean equals(Object anObject)

Compares this string to the specified object.

boolean equalsIgnoreCase(String anotherString)

Compares this String to another String, ignoring case considerations.

static String

format(Locale l,
String format,
Object... args)

Returns a formatted string using the specified locale, format string, and arguments.

static String

format(String format,
Object... args)

Returns a formatted string using the specified format string and arguments.

byte[] getBytes()

Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array.

byte[] getBytes(Charset charset)

Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array.

void

getBytes(int srcBegin,
int srcEnd,
byte[] dst,
int dstBegin)

byte[] getBytes(String charsetName)

Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array.

void

getChars(int srcBegin,
int srcEnd,
char[] dst,
int dstBegin)

Copies characters from this string into the destination character array.

int hashCode()

Returns a hash code for this string.

int indexOf(int ch)

Returns the index within this string of the first occurrence of the specified character.

int

indexOf(int ch,
int fromIndex)

Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.

int indexOf(String str)

Returns the index within this string of the first occurrence of the specified substring.

int

indexOf(String str,
int fromIndex)

Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

String intern()

Returns a canonical representation for the string object.

boolean isEmpty()

Returns true if, and only if, length() is 0.

static String

join(CharSequence delimiter,
CharSequence... elements)

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.

static String

join(CharSequence delimiter,
Iterable<? extends CharSequence> elements)

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.

int lastIndexOf(int ch)

Returns the index within this string of the last occurrence of the specified character.

int

lastIndexOf(int ch,
int fromIndex)

Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.

int lastIndexOf(String str)

Returns the index within this string of the last occurrence of the specified substring.

int

lastIndexOf(String str,
int fromIndex)

Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.

int length()

Returns the length of this string.

boolean matches(String regex) int

offsetByCodePoints(int index,
int codePointOffset)

Returns the index within this String that is offset from the given index by codePointOffset code points.

boolean

regionMatches(boolean ignoreCase,
int toffset,
String other,
int ooffset,
int len)

Tests if two string regions are equal.

boolean

regionMatches(int toffset,
String other,
int ooffset,
int len)

Tests if two string regions are equal.

String

replace(char oldChar,
char newChar)

Returns a string resulting from replacing all occurrences of oldChar in this string with newChar.

String

replace(CharSequence target,
CharSequence replacement)

Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.

String

replaceAll(String regex,
String replacement)

Replaces each substring of this string that matches the given regular expression with the given replacement.

String

replaceFirst(String regex,
String replacement)

Replaces the first substring of this string that matches the given regular expression with the given replacement.

String[] split(String regex) String[]

split(String regex,
int limit)

boolean startsWith(String prefix)

Tests if this string starts with the specified prefix.

boolean

startsWith(String prefix,
int toffset)

Tests if the substring of this string beginning at the specified index starts with the specified prefix.

CharSequence

subSequence(int beginIndex,
int endIndex)

Returns a character sequence that is a subsequence of this sequence.

String substring(int beginIndex)

Returns a string that is a substring of this string.

String

substring(int beginIndex,
int endIndex)

Returns a string that is a substring of this string.

char[] toCharArray()

Converts this string to a new character array.

String toLowerCase()

Converts all of the characters in this String to lower case using the rules of the default locale.

String toLowerCase(Locale locale)

Converts all of the characters in this String to lower case using the rules of the given Locale.

String toString()

This object (which is already a string!) is itself returned.

String toUpperCase()

Converts all of the characters in this String to upper case using the rules of the default locale.

String toUpperCase(Locale locale)

Converts all of the characters in this String to upper case using the rules of the given Locale.

String trim()

Returns a string whose value is this string, with any leading and trailing whitespace removed.

static String valueOf(boolean b)

Returns the string representation of the boolean argument.

static String valueOf(char c)

Returns the string representation of the char argument.

static String valueOf(char[] data)

Returns the string representation of the char array argument.

static String

valueOf(char[] data,
int offset,
int count)

Returns the string representation of a specific subarray of the char array argument.

static String valueOf(double d)

Returns the string representation of the double argument.

static String valueOf(float f)

Returns the string representation of the float argument.

static String valueOf(int i)

Returns the string representation of the int argument.

static String valueOf(long l)

Returns the string representation of the long argument.

static String valueOf(Object obj)

Returns the string representation of the Object argument.

Which methods of class String is used to extract a substring from a String object?

You can get substring from the given String object by one of the two methods:.

public String substring(int startIndex): This method returns new String object containing the substring of the given string from specified startIndex (inclusive). ... .

public String substring(int startIndex, int endIndex):.

Which of these method of class String is used to extract?

charAt() is the method of class String is used to extract a single character from a String Object. Hence, option(c) is the correct answer.

Which one of the following method is used to make substring?

Java String substring() The Java String class substring() method returns a part of the string. We pass beginIndex and endIndex number position in the Java substring method where beginIndex is inclusive, and endIndex is exclusive.

Which of these method of class String is used to obtain a length of String object?

Methods used to obtain information about an object are known as accessor methods. One accessor method that you can use with strings is the length() method, which returns the number of characters contained in the string object.

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